Windings for electrical apparatus



E. G. WINSTUN.

WINDINGS F05 ELECTRICAL APPARATUS.

APPLICATION FILED SEPT. I6. 1920. 1,386,828. Patented Aug. 9,1921.

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EABLE G. WINSTON, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOIR. T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

WIN'DIN GS FOR ELECTRICAL APPARATUS.

Specification of Letters Patent.

Patented Aug. 9, 1921'.

Application led September k18, 1920. Serial No. 410,735.

To all whom 'it may concern:

Be it known that I, EAnLE G. WINsToN, a citizen of the United States, residin at Pittsfield, in the county of Berkshire, i tate of Massachusetts, have invented certain new and useful Improvements in Windings for Electrical Apparatus, of which the following is a specification.

My invention relates to windings for electrical apparatus and has for itsobject an improved arrangement of parts .which 1s both economical and readily manufactured.

More specifically, my invention relates to an arrangement of windings havlng portions connected in multiple for poly-phase transformers and the like whereby the 1nterlacing of the conductors leading to the windings may be readily accomphshed 1n an economical manner.

In low voltage and particularly in electrlc furnace practice, where alternating currents of high values are employed, great difliculty is experienced in economlcally transmitting the current from the transformer which is generally employed to supply the current to the electrodes of the furnace or other apparatus served. In order to accomplish economical transmlssion, speclal consideration must be paid to both the shape and relative position of the conductors emlo ed.

p ue consideration for the so-called skim effect or tendency of the alternating current transmitted to seek the section of the conductor nearest the surface has led to the use of conductors of a relatively thin and flat shape, such as are often designated copper strap.

The other main consideration which determines the position of the conductors involves the roblem of reducing the selfinduction ofP these transmitting conductors. The solution of this problem is found in the practice of interlacing; that is, the conductorsand their leads to the transformer coils are arranged consecutively to have alternate polarities. Hence for any instant when the current in the first conductor of a bank leading from a furnace or like transformer makes the conductors polarity plus, the next should be minus, the next plus, etc.

When the windings of the supplying transformer are all on one or two lees, the desired sequence in polarities is hada by bringing the leads from the coils all out in one group and bending them up inconsecutive order. hen, however, the windings are on three or more legs, the conditions of clearance between the winding stacks on the dlferent legs do not as a rule permit the grouplng together of all the leads from two adJacent coil stacks. Consequently volumlnous and bulky cross-over structures have been heretofore employed, bringing the lead from the side where it necessarily emerges to the position of its desired sequence. Thls practice of employing crossovers was expenslve both to construct and 1n the necessary size of the tank or casing employed to house the transformer. w

In the practice of my invention the use of any cross-over construction is rendered unnecessary 1n polyphase transformers having windlngs on three or more legs, because make use of an improved arrangement of windings which permits bringing the leads from the coils out on either side of the winding stack 1n any desired order. This I accompllsh by making use of a certain number of reversely wound coils for changing the original sequence and hence achieving the desired sequence of polarities when the leads are brought out and conveniently grouped between adjacent coil stacks.

or a more complete understanding of the nature and objects of my invention, reference should be had to the following detailed description when taken in conjunction with the accompanying drawing in which:

-Figure l is a diagrammatic representation of a three-phase transformer embodying my invention, while Fig. 2 is a perspectiveview of a three-phase transformer as actually constructed removed from its casing which embodies my invention.

Referring now to the drawings, 10 denotes a core having a plurality of legs 11, 12 and 13, which support windings 14, 15 and 16, respectively.

The windings 14, 15 and 16 are of the interleaved disk coil type, in which the coils P denote high voltage coils and those designated by S the low voltage. Since the low voltage coils S are to supply currents of high values, it is with the interlacing ofr the leads to these coils that my invention principally relates.

In order to approximate conditions where my invention applies, it will be assumed that for reasons of clearance that it is permissible to group all the leads-of winding 15 neither on the left hand side, nor all on the right hand side, so that some must be grouped with the lead brought out from each of windings 14 and 16.

Consider now winding 14. Suppose that the coil designated S20 is wound as a right hand wound helical spiral (diagrammatically indicated by the backwardly iointing arrow) which starts from the top ead denoted 31, it will then finish with the bottom lead 32.

If at the instant of reckoning, the polarity of lead 31 is plus, then the polarity of lead 32 is minus as designated in the drawing. The sequence of alternate polarities is then had by bringing the lead 32 up on the right of lead 31. quence the coil denoted S-21 must be like coil S-20, that is, it must be a right hand wound helical spiral (denoted by the backwardly pointing arrow) so that its top lead 33 which would have plus polarity at the instant of reckoning is again led up to the right beside lea-d 32 and thus alternates with its polarity. Bottom lead 34, which has a negative polarity at the instant of reckoning, is then led up beside lead 33 on its right.

It thus appears that the desired sequence in polarities is had for the parallel connected low voltage coils of winding 14 by bringn of lead 34 and the top lead 36 led up to thek right of lead 35. The desired sequence of polarities require that lead 35 shall be plus at the instant of reckoning and that lead 36 shall be minus, which requires that coil S-22 should also be a left hand wound helical spiral (denoted by the forwardly pointing arrow).

Coil -S-23, according to theconditions of clearance assumed, will have its leads 37 and 38 brought up at the right side of winding 15.

In order however, to get the desired sequence in polarity in the leads, and in order also to avoid a cross-over construction, where my invention is practiced, the coil whose leads are differently grouped from another on the same windin axis must be oppositely wound. The coil -23 is therefore again a right hand wound helical spiral (denoted by the backwardly pointing arrow). The top lead 37 thus has plus polarity at the instant of reckoning while lead 38 is minus.

Similarly, to continue the In the winding 16, the coils S-24 and S-25 have their leads associated with leads 37 and 38. Since the leads from these coils, the same being denoted 26, 27, 28 and 29, are all in the same group, the coils are both wound in the same direction. The proper sequence, as will be seen, is had by bringing lead 26 from the bottom turn of coil S-25, etc.; the two coils being wound as left hand wound helical spirals (signified by the forwardly pointing arrows) to give this sequence.

To further exemplify the practice of my invention I now describe the embodiment shown in Fig. 2 which illustrates a three phase transformer particularly adapted to supply an electric furnace.

The core has three legs 41, 42 and 43 while the yokes are inclosed in upper and lower core clamps 44 and 45 respectively which also serve as supports for the three stacks of windings 46, 47 and 48 which respectively surround the three legs.

The leads 51 to 56 from the low voltage coils or portions of winding 46 are brought out all on the right side and led up in order and secured in the terminal board 70, which is secured on the top of core clamps 44. The three low voltage portions on this leg as a consequence are all wound in the same direction, that is, they may all be taken as right hand wound helical spirals.

In like manner the low voltage portions in the winding 48 have all their leads 63 to 68 brought out in order oii the left side thereof instead of the right, so that these portions also are all wound in the same direction. Since, however, the magnetic flux of leg 43 is of. the same direction, except for phase difference, as that of leg 41, these portions must be wound oppositely to those on leg 41, that is, they may be taken as left hand wound helical spirals.

Winding 47 has thev leads 57 to 62 of its low voltage portions brought out partly on one side to be grouped with leads 51 to 56 and partly on the other to be grouped with leads 63 to 68. The desired sequence of polarities is obtained and a cross-over construction avoided by takin the portion supplying current to leads 5 to 58 as a left hand wound helical spiral, while the portions supplying leads 59 to 62 with current are taken as right hand helical spirals.

By this construction, it is seen that a casing on which the cover 71 (mounted on the superstructure of the transformer) will fit, need have only sufficient clearance to clear the superstructure of the transformer without giving special consideration to the electrical factors involved.

Having now described an embodiment of my invention which is at resent the best means known to me for carrying the same into effect, I would have it understood that this is merely illustrative and that I do not mean to be limited therely prising in combination, a core to the precise details shown, nor restricte in the choice of recognized equivalents except as defined in my claims hereunto annexed.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. An electrical apparatus comprising in combination, a core provided with a plurality of legs, and windings on each of said le having portions provided with leads a apted for interlaced connection, a portion on one leg being wound in a direction oppo-4 site that of another portion thereon, the leads of said portions being arran ed in different groups whereby a sequence o alternate polarities among the leads is accomplished without cross-over connections.

2. A polyphase electrical apparatus comprising 1n combination,a core provided with a plurality of legs, and windings on each of' said legs having portions adapted to be connected in multiple with their leads arranged to have alternate polarities, a portion of the winding on one leg being wound in a direction opposite to. thatl of another portion thereon, said portions having their leads arranged respectively in different roups whereby the desired sequence of poxritles is had without crossover connections.

3. A polyphase electrical apparatus comrovided with a plurality of legs, and win ings on each of said legs having portions adapted to be connected in multiple withl their leads arranged to have alternate polarities, a predetermined portion of the winding on an intermediate leg being wound in a direction opposite that of the remaining portion thereon, the leads from the first named portion being brought out on one side of the winding and associated in a group, the leads from the remaining portion being brought out on the other side and associated in another group whereby the sequence of alternating polarities is had without the use of cross-over connections.

4. A three-phase transformer comprising in combination, a core having three legs, and windings on each leg, said windings having coils provided with leads adapted for connecting them in multiple and arranged to have alternate polarities, a predetermined number of coils on the central leg being wound in a direction opposite that of the remaining coils, the leads of the firstmentioned coils being brought out on one side and associated in one group and those of the remaining coils being brought out on the other side and associated in a second group.

In witness whereof, I have hereunto set my hand this thirteenth day of September, 1920.

EARLE G. WIN STON 

